What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

I am here to learn more about my own personal investments as well as seeking out learning opportunities from like-minded individuals.

Specifically, I am looking at partnering with an individual who owns securities (stock and mutual funds) having them take out a line of credit against their portfolio (SBLOC) at a low interest rate, and using that to purchase properties rather than using a mortgage.

I would add to this account every month, allowing me to pull from it whenever there was a large repair or capex event. 

I was also considering the REI expo in February so maybe I'll see you there.You're a self-proclaimed novice but I think many other members of the community would agree that you're well on your way given your potential cashflowing rental and equity.You seem to have a strong position which would allow you to keep growing your portfolio in the next few years.I'd recommend diversifying your RE portfolio the same way you're diversifying with other investments (REITs, Stocks, bonds etc.).

If a cash out refinance, many lenders will allow the cash out to satisfy the reserves requirement.DSCR lenders generally let you vest either individually or as an LLC.

Texas has some weird laws that don't allow all banks to have HELOC options.

You already seemed to conclude you are forcing this deal, I would agree unless there's a reason why this property will appreciate significantly in the near future and the 40 year amortization schedule allows you to hold on for that to occur. 

We also have a huge budget allowance from the city over the next few years to improve public transportation measures within the city.

HELOCs are not available because they are residential loans guaranteed by individuals and what you seek is a type of commercial loan or credit line which are available to seasoned companies with proven financial track record.